## XPA Changes: Changes For Users from XPA 1.0 and 2.0

## Summary

This document describes changes that will affect users who migrate from XPA 1.0 to XPA 2.0.

## Description

There have been a few changes that affect users who upgrade XPA from version 1.0 to version 2.0. These changes are detailed below.

- XPA commands no longer have a resolver routine (this is open to negotiations, but we decided the idea was dumb). For the SAOtng program, this means that you must explicitly specify the access point, i.e.,:

        cat foo.fits | xpaset SAOtng fits

  instead of:

        cat foo.fits | xpaset SAOtng

- By default, xpaset, xpaget, etc. now wait for the server callback to complete; i.e., the old -W is implied (and the switch is ignored). This allows support for better error handling. If you want xpaset, etc. to return before the callback is complete, use -n switch:

        echo "file foo.fits" | xpaset -n SAOtng

- The old -w switch in xpaset and xpaget is no longer necessary (and is ignored), since you can have more than one process communicating with an xpa access point at one time.

- The new -p switch on xpaset means you need not read from stdout:

        xpaset -p SAOtng colormap I8

  will send the paramlist to the SAOtng callback without reading from stdin.

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##### Last updated: September 10, 2003